This invention relates to the field of micro-sized mechanisms and, more specifically, to the use of micro-sized mechanisms to adjust optical components.
Precision assembly of micro-sized components is required in a variety of applications, for example, data storage systems. One type of data storage system, known as a magneto-optical (MO) storage system, provides storage of data on rotating disks. The disks are coated with a magneto-optical material and divided into magnetic areas referred to as domains. The data is stored as magnetization orientations in these magnetic domains. The magnetization is recorded in the MO material by focusing a laser beam of light to form an optical spot in a disk domain. The diameter of the focused spot may be smaller than approximately 1 micron (xcexcm). Information is read from a particular domain by using a less powerful laser beam, making use of the Kerr effect, to detect a rotation of polarization of light reflected off the disk""s surface.
Optical fibers connected to a head assembly are used to propagate light from the laser source to the disk. The head assembly contains optical components to direct the light from the optical fiber toward the rotating disk, and also to direct the light reflected from the rotating disk to the optical fiber. In one type of MO storage system, the head assembly is located on an actuator arm that moves the head assembly along a radial direction of the disk. As the disk rotates, the head assembly can be positioned over a particular domain. Precise alignment of the optical components in the head assembly is required to focus light to form the required optical spot on the disk.
Traditional optical storage systems use optical head assemblies containing large optical components. The resulting head assemblies are relatively massive, thereby increasing the time required to move the head to disparate regions over the disk""s surface. One method of manufacturing head assemblies produces optical components with sizes on the order of 250 xcexcm, thereby reducing the mass of optical head assemblies. One problem with using such head assemblies, however, is that greater precision is required to hold, align, and adjust the optical components in order to focus laser light onto an optical spot within a disk domain.
One prior art method of aligning optical components uses simple v-groove structures etched into silicon. In particular, the method uses these v-groove structures to align laser diodes and collimating lenses to optical fibers. These v-groove structures, however, do not allow for particular motion of the fiber with respect to the silicon v-groove and do not account for variations in fiber diameter or fiber core centricity. As such, precision adjustment of optical components with respect to each other after initial alignment is not possible.
Another prior art alignment method uses a series of trenches in a silicon block to align a laser diode chip, lens, and optical fiber. In particular, the components are used in a telecommunications application that operates at a wavelength of approximately 1.3 xcexcm. The method relies on the tendency of the components to self-align themselves due to the surface tension of molten solder connecting them.
One problem with such a method is that it may not be able to produce the necessary alignment tolerances to achieve a high coupling efficiency between optical components in applications that use a smaller light wavelength, for example, data storage systems (operating with a 410 nanometer light wavelength or less). The required alignment tolerances for a given coupling efficiency between optical components corresponds roughly to the wavelength of light propagated through the optical components. In addition, the required coupling efficiency, itself, is typically more stringent in data storage systems. As such, a self-alignment method may not be suitable for data storage or other critical visible light applications that use smaller wavelengths of light.
The present invention pertains to an apparatus for finely adjusting optical components. The assembly may include a first optic component, a substrate, and an adjuster. In one embodiment, the adjuster may include a first platform coupled to the first optic component, and a linkage of notched springs coupled to the first platform and the substrate. The linkage of notched springs provides for motion of the first platform along primarily one axis.
Additional features and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description that follows.